S B 




^/^W 






UNITED STATES DEPARTMENT OF AGRICULTURE 




BULLETIN No. 967 

'&• . _ •»; 






Contribution from the Bureau of Entomology 
L. O. HOWARD, Chief 




Washington, D. C. 



PROFESSIONAL PAPER 



October 14, 1921 



RESULTS OF WORK ON BLISTER BEETLES IN 

KANSAS. 

y 
F.rB. Milliken, Scientific Assistant, Truck-Crop insect Investigations. 



CONTENTS. 



Page. 

Introduction 1 

Economic importance 2 

Injury to crops 3 

Food plants 3 

Classification of species studied 4 

Description of Meloe sp ., 4 

Description of Cantharis reticu- 
lata Say 5 

Key to species of Epicauta and 
Macrobasis collected at Garden 

City, Kans 5 

Character of additional data on Mac- 
robasis and Epicauta 7 

Ri suits of work on Macrobasis 7 

Descriptive 7 

Macrobasis immacitlata Say 7 

Macrobasis unicolor Kirby 

Life history and habits 10 

Macrobasis immaculata Say 10 

Macrobasis unicolor Kirby ]2 



Page. 

Results of work on Epicauta 12 

Descriptive 12 

Epicauta maculata Say 12 

Epicauta cinerea Forst 13 

Epicauta scricans Lee 14 

Epicauta prnnsylranica De G__ 15 

Life history and habits 15 

Epicauta maculata Say 15 

Epicauta cinerea Forst 16 

Epicauta sericans Lee 17 

Epicauta prnnsylranica De G__ 17 

Irregular development 17 

Control measures 21 

Effect of arsenicals, contact insec- 
ticides, and repellents 21 

( ontrol measures in infested fields- 2.3 

Driving 25 

Summary of control measures , 25 



INTRODUCTION. 

In the drier portions of western Kansas and adjoining States the 
insect fauna is particularly rich in blister, beetles. Besides those of 
common occurrence elsewhere there are several species that are char- 
acteristic of the region. The native grasshoppers develop regularly 
in considerable numbers, thus insuring sustenance for some, at least, 
of the blister-beetle larvae. The beetles feed on native legumes and 
other plants that root deeply and make some growth even when 
cultivated crops and shallow-rooted weeds die of drought. 

The abundance of blister beetles in this region was noted by early 
entomologists, mostly systematists, who chanced through the western 
and southwestern United States ; but it remained for Dr. C. V. Riley, 

48562°— 21 1 






2 BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 

while entomologist of Missouri, to work out the first life histories of 
American species, and later as a member of the IT. S. Entomological 
Commission to extend his researches in this line. Riley studied only 
species of general occurrence and only two of them to completion, yet 
he announced as his opinion that the life histories of other species 
would be found strictly parallel to these. 

With the subsidence of outbreaks of the Rocky Mountain grass- 
hopper (Melanoplus spretus Uhler), the Commission directed its 
attention to the more pressing problems of thickly settled portions 
of the country. The writer knows of no further study of the eco- 
nomic relations or biology of American species of this group. 

The data on blister beetles that form the basis of this bulletin 
were collected, except as otherwise specified, since 1913. From 
March, 1913, to May, 1915, inclusive, the work was conducted at 
Garden City, Kans. From June, 1915. to June. 1917, inclusive, it 
was continued at Wichita, Kans. As the beetles do not occur there in 
sufficient numbers to supply the necessary material, work on con- 
trol measures was dropped, and only such life-history work was con- 
ducted as was possible with material collected on infrequent trips 
at irregular intervals to western Kansas. 

ECONOMIC IMPORTANCE. 

There has been a tendency among entomologists to class the west- 
ern species of blister beetles as beneficial. This arises from the fact 
that their larvae feed on the eggs of grasshoppers, from the ravages 
of which the early agriculture of the plains region suffered im- 
mensely. However, the species of grasshopper responsible for a 
large share of the injury, and the one that stands to-day an insect 
bogy to those of limited entomological knowledge, has disappeared 
from the scenes of its former activity so completely that specimens 
of it are curiosities to the new generation of entomologists. 

Only since the agricultural possibilities of the semiarid regions 
have been developed along diverse lines has it been possible to form 
a true estimate of the economic status of blister beetles. The pres- 
ence of extensive acreages of sugar beet, alfalfa, beans, and peanuts 
has allowed them to exhibit to the full their propensity as crop de- 
stroyers. The cultivation of large areas and the close pasturage of 
a great deal more have also altered the flora and environment to 
such an extent that the former equilibrium of the insect fauna has 
been disturbed. Cultivation has insured a much more extensive 
food supply for grasshoppers, and they have become distributed ac- 
cordingly; but much of this increase in the food of grasshoppers 
has not been accompanied by a corresponding increase in food suit- 
able for the adult blister beetles. The latter have, therefore, been 

i —horn 



LIBRARY OF CONGRI83 

ocratimi 

DOCUMENT** DIVISION 

■JiMiiiiBrtiti—inaiiirrT 



SB** 5 " 



BLISTER BEETLES IX KANSAS. 



unable to spread so widely. Pasturage or other disturbance inci- 
dent to the agricultural use of the land has proved a greater detri- 
ment to the blister beetles than to the grasshoppers. Even in locali- 
ties where blister beetles are most abundant repressive measures for 
grasshoppers have been found necessary. Also, where blister-beetle 
larvae infest a large percentage of the grasshopper egg capsules, they 
must destroy many larvae of the beefly Anastoechus nitidulis Fab., 
and of the hymenopterous egg parasite Scelio monticola Brues, 
neither of which is known to be injurious in any stage. The larvae 
of the beefly destroy a great many more grasshopper eggs than the 
larva? of the blister beetles, but are helpless against the latter when 
they enter the same egg capsules. 

It is questionable whether blister-beetle larvae have ever been suf- 
ficiently beneficial to offset the damage done by the adults. Cer- 
tainly they are now relatively of much less value than formerly. 
The group, therefore, must be considered injurious and will be- 
come more so with continued agricultural development of the semi- 
arid sections. 

INJURY TO CROPS. 

Blister beetles may devour only the petals and pollen of the 
flowers. They usually do this on beans, peanuts, and locust trees, 
and largely on alfalfa. On Irish potatoes, sugar beets, and to a 
lesser extent on the Russian olive, however, they commonly de- 
foliate the plant. In either case the actual injury to the crop depends 
on the stage of growth which the plants have reached. When they 
are near maturity the yield is lessened, but the crop is not a total loss. 
Unless drought prevails at the time of defoliation, sugar beets usu- 
ally put forth new leaves and continue their growth, but the effect 
of defoliation is recorded in decreased tonnage or sugar content, or 
both. A defoliation of Irish potato is usually disastrous, as is also 
the destruction of the blossoms of beans and of peanuts. 

FOOD PLANTS. 

Leaf-feeding insects, like the blister beetles, could not become as 
numerous in the semiarid regions as they do without the presence of 
some hardy native plant upon which they can feed during drought. 
At Garden City, Kans., the beetles feed upon the blossoms of the 
sunflower (Helianthus spp.), the goldenrod (Solidago spp.), the 
leaves and flowers of the few-flowered psoralea or scurvy pea (Pso- 
ralea tenuiftora) , and on other prairie legumes. They also feed ex- 
tensively on an introduced weed, the ground burnut (Tribulus ter- 
restris). 

The cultivated plants which they attack most extensively are the 
Irish potato {Solanum tuberosum) , the sugar and garden beets {Beta 



BULLETIN *. MJT , U. S. DEPARTMENT OF AGRICULTURE. 



vulgaris), alfalfa (Medieago satwa), the garden bean (Phaseolw 
spp.), the peanut {Arachis) hypogaea), and sweet clover (Jlelilotus 
alba). The writer has not noticed them feeding- much on other 
plants, but references to literature show that they attack a great 
variety of vegetation. 

As the beetles emerge they begin feeding on such plants as they 
find near by. Later they are driven to cultivated plants, because 
drought has killed the weeds or because they need a more abundant 
and continuous food supply to support them in their gregarious 
habits. 

CLASSIFICATION OF SPECIES STUDIED. 

The blister beetles belong to the coleopterous family Meloidae, the 
members of which contain in their bodies a substance that blisters 
when extracted and applied to the skin. Both subfamilies. Meloinae 

and Cantharinae, are represented in these 
studies, though only one genus of Meloinae 
was identified. This was Meloe, about 30 
specimens of an undetermined species of 
which were collected (Chttn. No. 2507). 
All of these were found along a short piece 
of roadway which was flanked on ope side 
by a field of wheat and on the other by a 
weedy prairie pasture. The species may 
have been only recently introduced in this 
locality, as it was but a few rods from the 
bank of a main irrigation ditch which 
comes directly from the Arkansas River. 
It was not to be found elsewhere at Garden 
City. Specimens were secured April 24, 
May 7, and May 19, 1914. On May 7 one 
pair was taken in copula, but no eggs were secured. The immature 
stages were not observed, nor were the beetles seen feeding except on 
the young Russian thistle. 

Description of Meloe sp. 

Anri/r. 

Near afer Bland, or barbarus Lee. (Chttn. No. 2507) : Length, S to 12.5 mm. : 
width. 3 to 4 mm.; elytra diverging, truncated, the body being widest across the 
abdomen near their tips; color black; rough and feebly shining. (Fig. 1.) 

Of the subfamily Cantharinae, two tribes, Nemognathini and 
Cantharini, were represented. 

The specimens of Nemognathini were identified as belonging to 
one genus and three species, N cmognatha lurida Lee, N. bicolor Lee, 
and X. piezata Fab. They were intermingling freely on blossoms of 




Fig. l. — Meloe afer: Adult. 
Enlarged. 



BLISTER BEETLES IX KANSAS. 




the bull-thistle (Cirsiwm htnceolatum) and on account of their inter- 
grading color patterns could easily have been referred to a single 
species. They were not observed in any injurious connection, and 
their immature stages were not found. 

The tribe Cantharini was represented by three genera — Macrobasis, 
Epicauta, and Cantharis. To Macrobasis and Epicauta belong the 
injurious species occurring at Garden City, Kans., and they are 
treated at length in this paper. Of the genus Cantharis only one 
species was identified, Cantharis reticulata Say, of which a very 
few specimens were collected. They are 
sufficient for only a brief description. 

Description or Cantharis reticulata 
Say. 

Adult. 

Length, about 15 to 25 mm. ; width, about 
4.5 to 7 mm. ; color black, except antennae and 
legs, which are dark brown. Elytra irregularly 
ridged, hence the name; head, thorax, and 
abdomen pitted and sparsely haired ; legs 
thickly haired. (Fig. 2.) 

The adults were taken on the bush 
morning-glory {Ipomoea leptophylla) , 
excepting one which was found on 
alfalfa. 

Besides Cantharis reticulata, the tribe Cantharini is represented 
at Garden City b} 7 at least 15 species, of which four belong to the 
genus Macrobasis and 11 to Epicauta. For the purposes of this 
paper the generic and specific distinctions are sufficiently set forth 
b}- the key, which has been adapted from Horn with the assistance 
of H. S. Barber, of the United States National Museum. 

KEY TO SPECIES OF EPICAUTA AND MACROBASIS COLLECTED AT GARDEN CITY, 

KANS. 

A. Second joint of antennae at least half as long as third Macrobasis. 

a. Black with posterior margins of abdominal segments gray. 

M. segmentata Say. 
aa. Gray, yellowish, or brownish, unicolorous or with markings. 

b. Prothorax usually with two longitudinal black stripes; elytra 
usually concolorous, sometimes with submarginal black stripes; 

basal joints of antenna? brown (fig. 3) M. albida Say. 

bb. Unicolorous. 

c. First joint of antennae as long as or longer than the sec- 
ond and third together. In the male it reaches to the 
occiput, and the second is at least twice as long and 

twice as thick as the third \t . un-icolor Kirby. 

cc. First joint of antennae similar in sexes, second joint 
shorter than third il/. immaculata Say. 



Fi< 



-'. — Cantharis reticulata : 
Adult. Enlarged. 



6 



BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 



AA. Second joint of antennae less than half as long as third Epicauta. 

a. Antennal joints elongate, loosely united, 
b. Unicolorous. 

c. Gray or yellowish E. cinerea Forst. 

cc. Black. 

d. Large, 25 to 30 inm. long E. corvina "Lee. 

dd. Less than 20 mm. long. 

e. Spurs of hind tibia stout, cylindrical ; length 

12 to 20 mm. (fig. 4) E. funebris Horn. 

ee. Spurs of hind tibia slender, acute at tip 
and unlike, the outer spur being broader ; 
length 8.5 to 14 mm E. Pennsylvania* DeG. 





Fig. 3. — The two - spotted 
blister beetle (Macrobasi* 

albida) : Adult, striped Fig. 4. — Epioauta funebris: 
variation. Enlarged. Adult. Enlarged. 

bb. Variegated. 

c. Gray or yellowish with black markings. 

d. With three longitudinal black stripes on each 

elytron E. lenmitscata Fab. 

dd. Spotted with black. 

e. Spots minute, scattering E. moculata Say. 

ee. Spots larger, crowded, sometimes coalescent. 

E. partialis Lee. 
cc. Black, elytra and prothorax margined with gray, and 

median line of prothorax gray E. marginata Fab. 

aa. Antennal joints short, closely united. 

b. Pronotum with pair of bare, smooth, black areas ; color reddish 

or grayish brown E. eallosa Lee. 

bb. Pronotum unmarked. 

c. Surface of pronotum moderately shining under vesti- 

ture E. ferruginea Say. 

cc. Surface of pronotum opaque E. sericans Lee. 

The only distinction between Macrobasis and Epicauta is in the 
relative length of the second segment of the antennae (figs. 5, 6). In 



BLISTER BEETLES IX KANSAS. 7 

Macrobasis it is at least half as long as the third and usually more. 
In Epicauta it is less than half as long as the third. 

The four species of Macrobasis are easily dis- 
tinguished, and no well-marked varieties in a c _ ; p3 3=e;:;;:K:K; ^ 
species were observed. But there is great 
variation in the shade of color, especially in FlG - 5 v T ^ e s P° r tless I blis 

' L « ter beetle (Macrobasts 

M. immaculata, and in the extent of the black immacuiata) : Antenna 
submarginal stripes on the elytra in M. albida. of male - Much en ~ 
These stripes next the outer and the inner 

margin of each elytron, if present, may extend so far as to unite 
at the distal end, forming a U that opens anteriorly. The black 

stripes on the prothorax may sometimes 
■ ==S::: =ac= c=;c=;c ^^ be lacking, but so rarely that it was not 

noted in the key. 

Fig. 6. — Epicauta corvina: » • ■, , ■, n -m • j_ 

Antenna. Much enlarged. As mi 8'ht be expected, Since Epicauta IS SO 

much more richly represented than Macro- 
basis, it has greater variation within its species: also the separation 
of the species is much more difficult. 

CHARACTER OF ADDITIONAL DATA ON MACROBASIS AND 

EPICAUTA. 

In the rearing work eggs of several species were secured in con- 
finement and hatched, giving authentic eggs and triungulins. No 
larvae have been carried through the growing stages. Attempts to 
do so were thwarted by the high percentage of parasitism which 
existed among grasshopper egg-capsules that were collected for the 
purpose, and the writer was unable to secure eggs of grasshoppers by 
confining them. Coarctate larva? were collected and kept under ob- 
servation during the succeeding transformations. These yielded 
authentic material for the identification and description of the later 
stages. 

In presenting the data relating to each genus the species on which 
they are most nearly complete will be considered first. 

RESULTS OF WORK ON MACROBASIS. 

descriptive. 

Macrobasis immaculata Say. 

Adult. 

Macrobasis immaculata is among the largest blister beetles found in Kansas. 
A number taken at Garden City averaged 17.5 mm. long by 4.5 mm. wide. 
Blatchley gives tbe limits of its variation in length as 13 to 23 mm. Color gray 
to light reddish brown. According to Blatchley, the sexes are distinguished by 
the third antennal joint in the male being longer than the second, but in the 
female of only equal len.sth or shorter. 



BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 




Egg. 

Length, 1.5 mm. ; width, 0.5 mm. ; shape almost cylindrical, but tapering 
slightly toward the posterior end ; color translucent yellowish white. 

Larva. 

Triungulin (fig. 7). — Length, 2.7 mm.; width, 0.5 mm. through the head; 
shape elongate triangular, tapering gradually to the posterior end, which is 
bluntly rounded ; color yellow or light brown, with lighter bands on the parts 
of segments that fold against one another when the 
body contracts in length ; legs 3-jointed, strong ; claws 
three in number (hence the name triungulin), slender, 
the two outer ones spinelike; eyes apparently only 
pigmented spots behind the antennae on the anterior 
part of and near the outer margins of the head ; 
mandibles flat, sickle-shaped, strong, with notched 
inner margins ; antenna? apparently 3-jointed, the third 
joint divided with the dorsal portion the larger and 
bearing several spinose hairs ; spiracles 9 in number 
and located above the lateral margins ; armature of 
abdomen consisting of spinose hairs, about 10 in a 
transverse row near the posterior margin of each 
segment, and about 6 in a row nearer the anterior 
margin, those in each row so placed as to be in rows 
with corresponding hairs on the other abdominal seg- 
ments ; anal segment with two diverging hairs one- 
fourth to one-third length of body, projecting poste- 
riorly from above its tip; hairs also regularly placed on thorax, head, and 
upper and outer surfaces of mandibles ; legs with stiff hairs projecting per- 
pendicularly on the femur but appressed on the tibia. 

Carabidoid and scarabaeidoid larvw. — 
Descriptions of these stages could not be 
secured from authentic specimens, as they 
were not reared. Collected larvse that 
were thought to be in these stages Avere 
similar to those figured by Riley * for 
Epicauta vittata. 

Coarctate larva (fig. 8). — Length, 11.5 to 
13.5 mm. ; width, 4.5 to 6.5 mm. ; shape 
elongate hemispherical, resembling the half 
of a peanut kernel if the ends of the latter 
were bent toward its flat side and its edges 
thickened ; color reddish brown ; entirely 
inactive, the skin rigid; location of ap- 
pendages shown by tubercular projections; 
limits of head shown by a constriction near 
the anterior end ; segmentation of body 
plainly shown dorsally but less distinct 
ventrally ; spiracles in shallow depressed line above the thickened edges. 
Third larva. — Measurements difficult to make, though greater than for the 
coarctate larva ; color white ; shape robust, fleshy, and much wrinkled, larva 



Fig. 7. — Macrobasis im- 
maculate- Triungulin. 





CL 



a. 



Fig. 8. — Macrobasis immaculata, co- 
arctate larva : <i. Lateral view ; 
a', ventral view. Enlarged. 



1 Riley, C. V., Packard, A. S., and Thomas, Cyrus. First Annual Report, U. S. Erit. 
Comm., Dept. Interior, XT. S. Gool. Survey. 1S77, pi. IV, fisrs. 4-7. 1S7S. 



BLISTEK BEETLES IN KANSAS. 



assuming a horseshoe shape when at rest; head horny, yellowish, with front 
almost vertical ; mandibles brown, curved ; antennas situated above the outer 
edges of the bases of the mandibles, apparently three-jointed, with two fleshy 
projections on the distal end of the third segment; lirst and second antennal 
segments with basal rings of brown and third segment brown for almost its 
entire length ; eyes minute black spots above the bases of the antennae ; sutures 
extending diagonally backward from the bases of the antennae, meeting at the 
median line above the middle of the front; labrum separated from the front 
by a brown suture; legs fleshy, jointed, the distal ends thickly studded with 
stiff brown spines ; spiracles on second body segment and on fourth to eleventh, 
inclusive. 

Pupa. 

Length, about 17 mm.; width, about 7 mm. (measured from tip to tip trans- 
versely extended femora) ; color yellowish white with translucent appendages; 
head appressed on prothorax until front is almost parallel with body; femur 
and tibia of each leg folded together and extending forward, upward, and out- 
ward ; tarsi extending posteriorly on the venter ; antennae extending pos- 
teriorly dorsal to the anterior and middle legs; posterior margins of pro- 
thorax and abdominal segments bearing stiff, curved spines. 

Macrobasis TRICOLOR KlRHY. 

Adult. 

Specimens of Macrobasis unicolor collected ;it Garden City, Kans., averaged 
about 13.6 mm. long and 3.4 mm. wide. Blatchley gives the limits of their 
variation in length as 8 to 15 mm. It is the slen- 
derest of our species (fig. 9) and the sides are almost 
parallel ; color ashy gray, sometimes with a yellow- 
ish cast, but more uniform than in any other species 
collected at Garden City, except the black ones. 

Egg. 

The eggs were not secured nor were the growing 
stages of the larvae identified. 

COABCTATE LARVA. 



Five specimens vary in length from 10 to 12 
mm., and in width from 4.5 to 5.5 mm. They are 
rather slender and of a yellowish brown color. In 
other ways they agree with the coarctate larvae of 
Macrobasis immaculata. 




Fig. 9. — The ash-gray blis- 
ter beetle (Macrobasis 
unicolor) : Female beetle. 
Enlarged. (Chittenden.) 



Third Larva. 

Smaller and more slender than the corresponding stage in M. immaculata, 
but otherwise similar thereto. 

Pupa. 



The only specimen measured was 10 mm. long by 3 mm. wide. Though 
smaller and more slender it was otherwise similar to the pupa of .1/. immacu- 
lata. 

48562°— 21 2 




10 BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 

LIFE HISTORY AND HABITS. 
MaGROBASIS IMMACULATA Say. 
OviPOSITION. 

The female of Macrohash 'immaculata deposits her eggs in small 
cavities (fig. 10) prepared in the soil wherever she may be feeding. 
In confinement no special preparation or arrangement could be ob- 
served. While on the staff of the Kansas Experiment Station the 
writer once observed oviposition in the field. The ovipositing female 
first came under observation about 3.30 p. m. She was busily engaged 
in excavating and continued thus as long as watched. The place was 
marked, and the writer returned at 6 o'clock to find her still at work. 
The next forenoon the spot where the beetle had worked had been 

smoothed over, nothing remaining to indi- 
cate the location of the eggs except the 
identifying marks. Careful excavation re- 
vealed the outlines of a bell-shaped cavity 
in which the dirt had been replaced and 
fig. io.— cavity prepared for loosely packed. In the center of the floor 
eggs by female of Mucrobaste AVas a smaller cavity that contained a mass 

immaculata. „ , , , , r™ 

oi several hundred eggs. Ihe eggs were 
about 1^ inches below the surface, and without definite arrangement 
or protective covering. 

The earliest date at which eggs were secured in confinement was 
July 22 and the latest September 9. 

Inc t-bation. 

As incubation proceeds the young larva soon becomes visible 
through the transparent shell. The body is translucent, distinctly 
segmented, and the head is closely appressed on the venter. The 
mouth parts extend backward below. The eyes are black, the tips 
of appendages brown, and the spiracles are ringed with brown. The 
hairs are closely pressed to the body, the two long ones on the anal 
segment being bent around so as to extend forward at the sides. 

Eggs deposited July 22 hatched August 3, and some deposited 
July 24 hatched on August 5 and 6. The incubation period is thus 
from 12 to 14 days in length, but this becomes increased during 
cooler Aveather. 

Habits and Growth of Larva. 

The newly hatched larva soon becomes active. Where the beetles 
are numerous during the summer the little triungulins soon abound, 
and close observation will discover them hurrying about over the 
ground. They go into every crevice and under every clod and piece 



BLISTEE BEETLES IX KANSAS. 11 

of vegetable matter. Their mode of locating and entering grass- 
hopper egg capsules has never been observed by the writer ; but a 
few weeks later the large, plump, white scarabaeidoid larvae and 
the reddish-brown coarctate larvae have been found in capsules of 
grasshopper eggs. Probably a large percentage of the triungulins 
fail to find grasshopper eggs and perish from starvation. The fact 
that not more than one larva is ever found in a capsule indicates a 
further mortality through struggles between rival claimants for 
egg masses, since where the triungulins are so numerous it seems 
certain that more than one would enter each capsule of eggs. 

All evidence that has been secured as to the rate of growth and the 
character of the accompanying transformations indicates that they 
are similar to and probably parallel with those decribed by Riley, 2 in 
the case of Epicauta vittata. 

On becoming full grown the larvae burrow away from the egg- 
capsules they have emptied, usually going much deeper, then turn- 
ing toward the surface. There each larva forms an elliptical cham- 
ber at a slight angle with the perpendicular, stiffens out with the 
head uppermost, and sheds the old larval skin, which remains around 
the posterior portion of the abdomen. This leaves the elongate 
hemispherical coarctate larva standing almost vertically on end in 
the old exuvium and supported near the anterior end by the dorsal 
portion resting against the wall of the cell. The depth at which 
coarctate larva? are found varies, being from 3 to 6 inches below the 
surface. 

The coarctate larva? have been found from late in summer until 
late the next spring. No scarabaeidoid larvae large enough to be- 
long to this species have been found during the winter or spring. 
This indicates that the species hibernates only in the coarctate larval 
stage. 

After the spring's warmth penetrates to the coarctate larva the 
rigid skin splits along the anterior portion of the dorsal line. The 
third larva wriggles out and burrows toward the surface. The 
writer's earliest record of this transformation is dated May 28, but 
another record gives pupation on May 27, so it is safe to say that the 
third larvae begin to appear in Kansas about May 20. 

Pupation. 

After a few days' activity the third larva has approached to within 
1 or 2 inches of the surface. Here it constructs an elongate cell 
at an angle with the horizontal of from 30° to 60°. It turns 
on its back therein (fig. 11) and begins transformation to the 
true pupa. The process requires several days, the exact time depend- 

- Riley, ('. V., Packard A. S., and Thomas, Cyrus. Op cit., p. 299. 



12 



BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 



ing on the prevailing temperature. Pupae have been secured be- 
ginning May 27 and continuing until August. Five that were han- 
dled in confinement be- 
tween May 27 and July 2-1 
had an average pupal pe- 
riod of 18 days. 

Emergence <>f Adult. 

As the time for emer- 
gence approaches, the tips 
of the appendages begin to 
darken. The coloration 
spreads gradually through- 
out the appendages and 
into the body. Several 
days before the emergence 
of the adults twitching 
moA 7 ements begin in the 
tarsi. These become more 
vigorous toward the end of 




Fig. 11. — Pupa of blister beetle in situ in cell. 



the pupal period, finally involving the legs and oral appendages. 
During its struggles the beetle rights itself and explores the narrow 
confines of its chamber. A thin, transparent, parchment-like mem- 
brane loosens on the surface of its body and is torn beyond recogni- 
tion by the sharp tarsal claws. Adults from 
pupae that have formed against the walls of 
glass containers have remained in the cells 
for several days after transformation before 
digging to the surface. Whether or not such 
is the case when light is excluded was not 
determined. 

Macrobasis ttnicolor Kirby. 

The data secured on Macrobasis unicolor 
add nothing to the general account given for 
Macrobasis immacvZata. The third larvae 
have been collected by April 15, and eight 
specimens secured by that time had yielded 
the adults by May 30. The data on M. uni- 
color indicate that it, also, hibernates as coarc- 

tate larva. 

RESULTS OF WORK ON EPICAUTA. 

descriptive. 

Epicauta maculata Say. 

Adult. 

Adult specimens of Epicauta maculata (fig. 12) varied from 10 min. long 

by 2.25 mm. wide to 13 mm. long by 3.5 mm. wide, which makes it one of the 




Fig. 12. — The spotted blis- 
ter beetle (E picaut a 
macula t a). Enlarged. 
(Chittenden.) 



BLISTEB BEETLES IX KANSAS. 



13 



smallest of cur common blister beetles. The color may be either light gray 
or yellowish, with scattered naked spots of the black background. The black 
spots vary both in size and location, being barely dis- 
cernible on some beetles and at least 0.3 mm. in di- N^ 
ameter on others. n. 

Egg. 

The egg of this species resembles that of M<i<r<>- 
basis immaculata, but is smaller. 

Larva. 

Triungulin (tig. 13). — Length, about 1.25 mm.: 
width, about 0.4 mm. ; widest in front of middle of 
head just behind eyes, from which point the head 
tapers posteriorly for the last half or more of its 
length. In this respect it agrees with triungulins of 
Epicauta pennsylvanica and E. lenmiscata, 3 but dif- 
fers from Riley's figure of ;■:. vittata* The head of 
the latter is parallel-sided, resembling Macrobasis 
immaculata, but differing in having a very short pos- 
terior portion or neck and in having the eyes located about the middle of 
the length of the head. In all triungulins examined by the writer the eyes 
are located much nearer the anterior portion of 
the head. 

In other respects the triungulin of this species re- 
sembles that of Macrobasis immaculata (p. S). 

Active larva'. — Neither the growing stages nor the 

third larva were recognized so they could be described. 

Coarctate larva. — The writer's records show one 

coarctate larva that measured !> mm. long by 4 mm. 

wide which yielded an adult of this species. 

Pupa. 




Pig. 18. — Epicauta macu- 
la tu: Triungulin. En- 
larged. 




Fig. 14.— Epicauta cine- 
yea: Adult. (Chitten- 
den.) 



The pupa of this species was not described for lack 
of authentic material. It is similar in color and ap- 
pearance to that of Macrobasis immaculata, but much 
smaller. 

Epicauta cinerea Forst. 

Adult. 

Length of adult Epicauta cincrca (tig. 14), from S to 17 mm.; width, 1.75 to 
4 mm.; shape slender, with sides of elytra almost parallel; color, bluish to 
light or yellowish gray. 



Egg and Active Larva. 

Neither the egg nor any of the active larval stages of this species were secured 
for descriptive purposes. 



3 Triungulins of this species were kindly furnished by Mr. Thos. II. Tones of the Bureau 
of Entomology. 

4 Riley, C. V., Packard, A. S.. and Thomas, Cyrus, op. cit., PI. IV. fls. 2. 



14 



BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 



COAKCTATE LABVA. 

Length of coarctate larva (fig. 15), 7.45 mm.; width, 4.0S mm.; 28 specimens 
varied in length from G.25 to 9 mm. and in width from 3.25 to 5 mm. Shape 
much more robust than that of the coarctate larva of any other species thus far 






Fig. 15. — The 



jray blister beetle (Epicauta cinerea) 
larva ; b, third larva; c, pupa. 



a, Scarabaeidoid 



secured, being almost straight longitudinally on the venter and without the 
angular lateral ridges, thus leaving them almost circular in abdominal cross 
section ; color a rich reddish brown, darker than any other species with which 
Ihe writer has worked. 

Pupa. 

The single pupa (fig. 16, c) of this species 
which was measured had a length of 12 mm. 





a b 

Fig. 10. — Epicauta cinerea: a, Coarctate 
larva, lateral view ; b, coarctate larva, 
ventral view. 




Fig. 17. 



-Epicauta sericans: Adult. 
Enlarged. 



and a width of 4 mm. In shape, color, and general appearance it resemhles 
the pupa of Macrobasis immaculata, but is not so large. 

Epicauta sericans Lec. 

Adult. 

Of 29 adult specimens of Epicauta sericans (fig. 17) the variation in length 
was from 9.5 to 13 mm., with an average of 10.8 mm. ; color, light reddish brown 
through yellow and gray to almost silvery ; antennas reaching to the elytra, the 
segments except the second being nearly as broad as long. The second segment 
is nearly twice as long as thick ; sides of elytra nearly parallel. 



BLISTER BEETLES IN KANSAS. 



15 



Egg and Young Larva. 
The egg has not been secured or the growing stages of the larva recognized. 

COABCTATE LAKVA. 

The average of 10 coarctate larvae was 6.875 mm. in length by 3.8 mm. in 
width. They are reddish brown, but not so dark as those of E. cinerca. and 
the lateral ridges are present and distinctly angular. 

Tuna) Larva. 

The third larva? are 7 to 8 mm. long by 2.5 to 
.'5.5 nun. wide. In shape, color, and general appear- 
ance they resemble those of Macrobasis itnmaculata. 
Pupa. 

A description of the pupa has never been secured. 

EPICAUTA PENNSYLVANIA De G. 

Adult. 
Epicauta pennsytvanica (tig. 18) is the smallest 
of the black blister beetles that occur in Kansas. 
Of 18 specimens, the length varied from 8.5 to 14 
mm., averaging 10.3 mm., and the width from 2 to 
4 mm., averaging 2.SS mm. ; shape rather slender ; 
color dull black. 

Egg. 




Fig. IS. — The black blis- 
ter beetle (Epioauta 
pennsylvanica) : Adult. 
Enlarged. (Chittenden.) 



The egg resembles that of Macrobasis immaculata, but is much smaller. 

Triungulin Larva. 

Length of triungulin larva (tig. 19) about 1.3 mm.; width about 0.3 mm., 
widest through the head about midway of its length, which is just behind the 
eyes, and tapering to the prothorax, into which it telescopes slightly ; color, 
brownish yellow, translucent. In shape and general appearance it resembles the 
triungulin of Macrobasis immaculata. 

None of the other larval stages have been secured, even the coarctate larva of 
this species having escaped recognition. 

life history and habits. 

Epicauta maculata Say. 

Oviposition. 

While on the staff of the Kansas Experiment 
Station the writer observed oviposition by a fe- 
male of Epicauta macul-ata, as well as by a female 
of Macrobasis in i maculata. Both were working 
at the same time, being discovered only a few 
yards apart in the edge of a field. The process was 
identical with both females, lasting from before 
3.30 p. m. until after 6 p. m., as described under 
M. immaculata. The cavities to receive^ the eggs 
were made exactly alike — bell-shaped, with the 
flaring end down and the eggs reposing in a 
further depression at the center of the bottom of 
but the cavity made by E. maculata was only about 1 inch 




■Epicauta 

anica: Tri- 

Enlarged. 



the bell 



16 BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 

deep, as compared with 1 1 inches for the other. Several hundred eggs 
were in each nest. 

In confinement eggs have been secured from July 27 to September 
22. Confined females lose their instinct for careful oviposition, 
placing their eggs under a clod or leaf, or scattering them about on 
the surface without covering. 

Incubation. 

Incubation proceeds as described for Maerobasis immaculata. 
Eggs secured July 31 hatched August 18, and others deposited Au- 
gust 1 hatched August 22, giving an incubation period of from 18 
to 21 days. 

Habits and Growth of Larva. 

The newly hatched larva? soon become active. Their activities 
parallel those described for the triungulin of Maerobasis immaculata. 

The coarctate larva? are found near the surface, being but little 
deeper than the lower ends of the grasshopper egg capsules. Many 
are taken directly from the capsules. In confinement one third-stage 
larva appeared on May 6, the pupa was fully formed on May 12, 
and the adult came forth on May 25. The adults appear in numbers 
earlier than those of any other species of Cantharini taken in this 
region, this fact being corroborated by field observations. Since 
eggs were secured on September 27 it is evident that the adults occur 
throughout the summer. 

Epicauta cinerea Forst. 

Oviposition by Epicauta cinerea has never been observed, nor have 
the habits of the larvae preceding the coarctate been studied. 

The coarctate larva? have been collected at all seasons of the year 
and wherever grasshopper eggs are to be found. They occur from 
2 to 5 inches below the surface in nearly upright cells, in w T hich the 
larva? are disposed as described for Maerobasis immaculata. The 
earliest date at which third larva? have been collected was between 
April 12 and April 16. They are frequently found during the last 
week in May. 

According to the writer's records the earliest pupation in confine- 
ment occurred May 8 ; but an adult for which the pupation was not 
recorded emerged on the same date, thus indicating pupation at 
least 10 days earlier. Other transformations follow rapidly and 
continue through the summer. From the dates recorded for the 
transformation of this species it would seem that its appearance in 
the field should precede that of Epicauta ?naculata, which, as stated 
above, is the earliest to appear of the Cantharini of this region. The 
apparent contradiction is reconciled by the occurrence of most of 
the coarctate larvae at greater depths than those of E. maculata, 



BLISTER BEETLES IX KANSAS. 17 

which prevents the reception of sufficient heat to start activity earl}' 
in the season. Only those individuals of E. cinerea that are near 
the surface appear with the main brood of E. maculata. 

Epicauta sericaxs Lec. 

Adults of Epicauta seHcans have been collected from June 6 to 
September 11. They are commonly found feeding in flowers on 
many kinds of plants, often being taken on sunflower (Ilelianthus 
spp.), other Composite?, the scurvy pea (Psora-lea tenuiffora), alfalfa, 
peanuts, and other cultivated legumes. 

The eggs have not been secured or the growing stages recognized. 
The coarctate larva? have been collected during the fall, winter, and 
spring, and emergence begins early in June. For these reasons this 
species is believed to develop normally one generation annually, 
hibernating as coarctate larva ; but instances of retarded develop- 
ment have occurred, and these are considered under the proper 
heading. 

Epicauta pexxsyevanica De G. 

The adults of the small black blister beetle have been collected 
at Garden City, Kans., from August IT to November 11. At the 
latter date about half the adults had died, and the remainder were 
so stiff from cold that they could not cling to vegetation. The} 7 were 
first found on blossoms of the goldenrod (SoUdago spp.). but later 
fed on the blossoms of the many-flowered aster (Aster ?nultiflora), 
alfalfa, and a few other plants. Eggs were not found in the field, 
but were secured from adults confined on earth in a battery jar. On 
October 20 a cluster of 363 was deposited about half an inch below 
the surface. The eggs hatched on November 15, which was too 
late for development to proceed. This agrees with Riley's state- 
ment 3 that the species evidently hibernates as the triungulin. 

IRREGULAR DEVELOPMENT. 

During the progress of these investigations some marked varia- 
tions were observed in the time required for development. Of 
active, grown larva? collected at Garden City, Kans., during the 
period from April 12 to 16, 1916. three transformed to coarctate 
larva? of Epicauta cinerea by May 7. When examined again on 
May 29 they were found dead as third larva?, having perished from 
lack of moisture. Under the circumstances it is impossible to say 
whether these specimens were mature scarabaeidoid or the third 
larva? when collected. Most specimens of Epicauta. cinerea that have 

5 Riley, C. V.. Packard A. S., and Thomas, Cyrus. Op cit., p. 301. 



18 



BULLETIN 967, V. S. DEPARTMENT OF AGRICULTURE 



been reared came from coarctate larvae that were collected during the 
fall and winter. 

Seven mature coarctate larvae of one type, collected during the 
winter of 1913-14 were placed on soil in a perforated tin box. Dur- 
ing the summer the box was buried in the insectary at a depth of 
about 2 inches and forgotten. The writer chanced upon it again 
November 25, 1914, finding in it six coarctate larvae, one dead third 
larva, and seven cast coarctate skins. Only one explanation is pos- 
sible. The coarctate larva? all transformed to the third larvae, and 
six of them reverted to the coarctate condition again. The seventh 
perished. On May 30, 1915, the six coarctate 
larvae were separated into two lots of three each. 
One lot was placed in dry earth, the other in 
damp earth. The former showed no signs of 
activity. Of those in moist earth, one had de- 
cayed by July 2, another had transformed to 
third larva, and the third specimen remained 
unchanged and apparently healthy. The third 
larva continued its transformations, and on July 
24 yielded an adult of Epicauta xericans. The 
four unchanged coarctate larvae were stored in 
dry soil until the spring of 1916. Upon being 
moistened they decayed at once. 

A coarctate larva obtained during the winter 
of 1913-14 did not yield the adult until July 7, 
1915. This proved to be Macrobasls immaculata. 
Riley ° reports cases of retarded development in Epicauta vittata 
(figs. 20, 21). From the same batch of eggs he had beetles mature 




Fig. 20. — Striped blister 
beetle i Kpicauta rit- 
tiila) : <i, V e in a 1 o 
beetle ; h, eggs. En- 
larged. (Chittenden.) 



Regarding one which required three 



in one, two, and three years, 
years he wrote as follows : 

In this case the individual, though submitted to exactly the same conditions 
as the other specimens, which had simultaneously hatched with it — but which 
went through all their transformations within either one or two years — re- 
mained dormant for nearly three years, with their repeated changes of season 
and temperature. With the exception of the first winter, when it was kept 
indoors without freezing and when development should have been presumably 
hastened, the specimen was kept in a tin box buried the proper distance beneath 
the ground out of doors, so as to be as nearly as possible under natural con- 
ditions. 

Continuing the discussion of retarded development, he says: 

In the case of our blister-beetles, depending as they do on locust eggs, and 
especially in the case of those which feed particularly on the eggs of migratory 
species, it is not difficult to perceive how this trait may prove serviceable to 
the species possessing it. Migratory locusts occur in immense numbers in some 



"Riley, C. V., Packard; A. S., and Thomas, Cyrus. Second Report. U. S. Ent. Comm. 
Kept. Interior, 1878 and 1879, pp. 260-261. 1880. 



BLISTER BEETLES IN KANSAS. 



19 



particular part of the country at irregular intervals, and there are periods or 
years of absolute immunity from their presence in the same regions. The young 
blister-beetles' that hatch the year following the advent of the locusts in 
immense numbers may frequently tind few or no locust eggs upon which to 
prey, and the great bulk of them would, as a consequence, perish ; while the 
young from such exceptional individuals as should not develop till two, three, 
or more years after a locust invasion might stand a much better chance of 
finding appropriate food and of thus perpetuating the species. In this case 
and in most other cases of retarded development with which we are familiar, 
the exceptional retardation may and does become a benefit to the species, 
enabling it to bridge over periods of adversity. And we can see how, by the 
preservation of such favored individuals, the habit of irregular development 
may have become fixed in the species as a consequence of surrounding con- 
ditions and circumstances which render it advantageous. 






/ 



Fig. 21. — Striped blister beetle (Epicauta vittata) : c, Triungulin 
larva; </, second or caraboid stage; e, same as d, doubled up as in 
pod ; f . scarabacoid stage ; g, eoaretate larva. All except e enlarged. 
(After Riley.) 

In these two paragraphs Kiley points out the tendency to irregular 
development which is exhibited in blister beetles, and the benefit 
which it undoubtedly is to the species. He discusses the irregularity 
as a tendency which is already acquired, though indicating its origin 
" as a consequence of surrounding conditions and circumstances." 
Whether he believed that irregular development could be induced in 
individuals by subjecting them to certain conditions he does not 
state. 

During retarded development the additional time involved is spent 
in the eoaretate larva stage. Low temperature inhibits development 
in any stage, but in the other stages activity is resumed with increased 
temperature. The hardy triungulin can survive for two or three 
weeks without food, but Rile} 7 reports 7 that the first molt is usually 
experienced about the eighth day after the first taking of food, in- 
dicating that normal development begins with reception of nourish- 
ment. Entering an egg-capsule automatically limits the food a 



7 Riley, C. V., Packard, A. S., and Thomas, Cyrus. First Annual Report U. S. Ent. 
Comm. Dept. Interior, U. S. Geol. Survey, 1877, p. 299. 1878. 



20 BULLETIN 967, V. S. DEPARTMENT OF AGRICULTURE. 

triungulin can secure. If the eggs in a capsule fall short of the 
minimum requirement to carry the larva to maturity it perishes ; if 
they exceed this minimum the difference is registered by the size of 
the beetle which develops. Consequently, in a given species there is 
great variation in size of the adults. The third larva is injuriously 
affected by insufficient or excessive soil moisture; however, the vari- 
ation or limits in which it is safe are commonly prevalent in semiarid 
regions during spring and early summer. The pupae are exceedingly 
sensitive, being injuriously affected by excessive soil moisture, han- 
dling, high temperature, or a soil rich in humus. Even prolonged 
high humidity injures them. Many on which a little earth dropped 
or that are exposed during an examination gradually turn dark and 
decay. 

The coarctate larvae, on the other hand, are resistant to handling, 
to exposure, to drying, or to any soil disturbance that does not crush 
them. They have even become overgrown by saprophytic soil fun- 
gus while in storage without loss of vitality. Excessive soil moisture, 
however, or continued high humidity, such as is necessary to pro- 
duce conditions that favor the development of fungus, is usually 
detrimental. The position of the coarctate larvae in the soil facili- 
tates drainage, standing, as they do, on end in the old exuvium and 
touching the soil only in the dorsal region of the prothorax. Treat- 
ment to which they were submitted by the writer also demonstrated 
their ability to withstand extreme exposure and drying. Coarctate 
larvae that remained for months in open containers without soil, in 
open containers on dry soil, and buried in pulverized dry soil have 
transformed shortly after being placed in moist soil. 

When coarctate larvae are very dry during the spring and early 
summer the rigid skin often splits immediately if water is thrown 
directly upon it, the larvae emerging within a few minutes. Such 
dry coarctate larvae also soon transform when placed on moist earth. 

Coarctate larvae that are kept dry during the spring and summer 
may or may not give forth the third larvae when moistened in the 
fall. The instance cited of seven that were buried and forgotten 
and later found to have become third larvae, six of which reverted to 
the coarctate stage, illustrates another mode of behavior of such 
specimens. During the time they were buried the insectary was 
flooded by run-off irrigation water from an adjacent field. The 
floor was barely covered by water and dried quickly, especially in 
the end where the box was buried. It is possible that enough water 
penetrated the box to initiate development, but not to complete it. 
The six larvae that resumed the coarctate stage did so as a protective 
measure, or else the coming of cold weather caused this resumption. 
The writer attributes their reversion to one of these alternatives. 
Granting the correctness of these deductions, it indicates a more 



BLISTER BEETLES IN KANSAS. 21 

complete adjustment to the semiarid conditions under which they 
thrive best than anything in Riley's writings that have come before 
the writer. 8 

An attempt will be made to apply these conclusions to field con- 
ditions as found in western Kansas: The rainfall is most abundant 
in spring; it gradually decreases through the summer, but increases 
again toward fall. The coarctate larvae that receive sufficient mois- 
ture transform as soon as the temperature becomes favorable, and 
usually are able to complete their life history before the moisture 
becomes deficient. If for any reason — lack of rainfall, impervious 
soil, or deflection of rainfall b/y sheltering vegetation — the soil mois- 
ture is deficient, the coarctate larvae remain dormant. If, after their 
appearance, the third larva? find insufficient moisture they revert to 
the coarctate stage, and they may behave similarly if low tempera- 
ture occurs. It is not known how long coarctate larvae can remain 
dry in undisturbed cells without impairment of their vitalit}^. 

The preceding discussion of the environmental factors responsible 
for the phenomenon of irregular development in blister beetles is 
intended not only to present the author's interpretation of his data, 
but to direct attention to what he believes is a fertile field for re- 
search on the factors influencing insect development. The incom- 
pleteness of the data will insure the reception of this paper as a re- 
port of progress of work done during this period with the available 
time and material, instead of as a definite statement of results and 
conclusions. 

CONTROL MEASURES. 

While the writer was engaged in the work on life history and 
habits of blister beetles, tests were made of remedies whenever an 
opportunity occurred. The work on remedies may be considered 
under two heads: (1) Effect of arsenicals, contact insecticides, and 
repellents; and (2) control measures in infested fields. 

EFFECT OF ARSENICALS, CONTACT INSECTICIDES, AND REPELLENTS. 

Arsenicals. 

• 

The widely prevalent idea that arsenicals are ineffective against 
blister beetles was left in doubt in the earlier tests of the poisons by 
the writer; the beetles would disappear, leaving but few dead ones 
visible. In order to learn definitely whether the beetles were killed 
by the poisons single beet plants were sprayed with each kind and 
beetles confined thereon in cages, 10 beetles being placed in each 
cage. The experiment was conducted three times during July, 1913, 
and the data are given in Tables 1, 2, and 3. The kind of poison 

8 The writer has read only the reports of the U. S Entomological Commission. 



22 



BULLETIN 9&1, U. S. DEPARTMENT OF AGRICULTURE. 



used is indicated at the heads of the columns, with its strength in 
pounds to so many gallons of water. With Paris green an equal 
quantity of quicklime was used. 

Table 1. — First experiment in the use of arsenicals, contact insecticides, and 
repellent* against blister beetles; begun June 30, 1913. 



Date. 


Number of beetles dead after 
with — 


spraying 


Paris 
green, 
1-1-25. 


Zinc 

arsenite, 

1-20. 


Lead 

arsenate, 

1-12*. 


Bordeaux 
mixture, 
4-4-50. 


July 1.. 
2.. 
3.. 
4.. 



6 

10 




3 

8 
10 







5 







1 


5.. 




7.. 











When the experiment was discontinued the beet sprayed with Bor- 
deaux mixture was defoliated with only one beetle dead, and the one 
sprayed with lead arsenate was badly damaged with only five of the 
beetles dead. Lead arsenate made such a poor showing that its 
strength was doubled in the second experiment. 



Table 2. 



-Second experiment in the use of arsenicals, contact insecticides, and 
repellents against blister beetles; begun July 7, 1913. 



Date. 


Number of beetles dead after spraying 
with— 


Paris 
green, 
1-1-25. 


Zinc 

arsenite, 

1-20. 


Lead 

arsenate, 

1-6*. 


Bordeaux 

mixture, 

4-1-50. 


July 8. 
9. 
10. 
11. 



3 
10 



10 



2 
8 
10 





3 




12. 















The beets sprayed with Bordeaux were again badly defoliated, 
but the increased strength of lead arsenate prevented much damage. 

Table 3. — Third experiment in the use of arsenicals, contact insecticides, and 
repellents against blister beetles; begun July 22, 1913. 





Number of beetles dead after 


spraying 


Date. 




with— 














Paris 


Zinc 


Lead 


Bordeaux 




green, 


arsenite, 


arsenate, 


mixture, 




1-1-25. 


1-20. 


1-10. 


4-4-50. 


July 24. 


1 





1 





25. 


3 


2 


1 


2 


26. 


7 


5 


2 


2 


28. 


10 


7 


4 


7 


29 
30 




10 


8 
8 






7 







BLISTER BEETLES IN KANSAS. 23 

During these experiments Paris green has, except in one instance, 
killed the beetles in less time than zinc arsenite. Its killing time has 
been consistently shorter throughout than lead arsenate in quantities 
that it is practicable to apply. The results from Bordeaux mixture 
do not justify its use in this connection. Of the beetles poisoned 
during these experiments very few remained in sight. Most of them 
were to be found among the bases of the stems or under clods about 
the base of the plant. 

Repellents. 

To determine what substances possess the greatest repellent prop- 
erties, part of a cluster of beet plants was sprayed with Paris 
green, part with Bordeaux mixture, part with fish-oil soap, part with 
nicotine sulphate, and the remainder with water. A large screen 
cage was then set over the beets and about 70 beetles introduced. 
They scattered over the plants indiscriminately, but none fed on the 
ones treated with Paris green and Bordeaux. A little foliage was 
eaten from the plants treated with nicotine sulphate and soap. The 
beets sprayed with water were defoliated. 

( \ INTACT I N.SECTICIDES. 

Lime-sulphur in strengths up to 30 per cent did not produce satis- 
factory results. The weaker solutions had no effect on the beetles 
and the stronger ones stunted the beets. 

Whale-oil soap, 1 pound to 2 gallons of water, killed beetles that 
could be thoroughly wet, but injured both sugar beets and potatoes 
on which the applications were made. Xo other contact insecti- 
cides were tested. 

CONTROL MEASURES IN INFESTED FIELDS. 

On June 23. 1913, blister beetles attacked a half-acre field of 
sugar beets at the Garden City branch of the Kansas Experiment 
Station. Most of them were the small-spotted blister beetle (Epi- 
cauta maculata) . but the outbreak included a feAv of a large gray 
blister beetle or spotless blister beetle {M acrobasis immaculata) . The 
little four-leaved plants had been stripped to the midribs over most 
of the field, and on the remainder the beetles were feeding. They 
were also crossing the road into a patch of Irish potatoes. 

The beets where the beetles were feeding were sprayed with 1 
pound of lead arsenate in 9 gallons of water. Part of the potatoes 
were sprayed with 1 pound of zinc arsenite in 32 gallons of water, 
part with 1 pound of Paris green and some lime in 40 gallons of 
water, and the remainder left as a check. The beets were so small 
and so badly eaten before being sprayed that they never recovered. 



24 BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 

The sprayed potatoes were only slightly injured by the beetles, but 
the unsprayed ones were defoliated (fig-. 22). 

On July 5 a small patch of potatoes, grown by Dr. C. O. Town- 
send of the Bureau of Plant Industry for experimental purposes, was 
attacked by blister beetles of several species. The potatoes were 
being sprayed with Bordeaux mixture, so Paris green was added 
thereto for part of the patch and zinc arsenite for another portion. 
The potatoes designed to be left as a check on the Bordeaux treat- 
ment were sprayed with Paris green alone. These potatoes suffered 




Fig. 22. — Field of potatoes attacked by blister beetles ; strip through middle left un- 
sprayed. Sprayed on left and on extreme right. (Photo by Lill, Bureau of Plant 
Industry.) 

very little during the attack. Another invasion occurred three 
weeks later, at which time the potatoes were all sprayed with Paris 
green, 1 pound to 25 gallons of Bordeaux Avhere the latter was used, 
and the same strength alone on the remainder. No damage resulted 
from the second attack. 

Three acres of sugar beets belonging to Mr. D. A. Sheaks, of 
Garden City, Kans., were attacked by blister beetles that gathered 
in one edge of the field, most of them being large beetles (M acrohasis 
hnmaculata) . On July 26 about half of the field, including the in- 
fested portion, was sprayed with \\ pounds of Paris green and some 
stone lime in 50 gallons of water. The beetles ceased their injury on 
the sprayed portion of the field, those that escaped collecting on 
beets on the unsprayed area. Xot more than 25 per cent of them 
were killed. 

On July 28 blister beetles from a freshly cut field of alfalfa 
gathered in a one-acre field of beets. About one-third of the patch 



BLISTER BEETLES IN KANSAS. 25 

was sprayed, 1 pound of Paris green and some lime in 25 gallons of 
water being used. Another half-barrel of the solution was then pre- 
pared, the nozzles were changed for others having smaller openings, 
and the spraying was completed, only about a third of the second 
half-barrel of solution being used. The next morning dead beetles 
were numerous among the bases of the leaves and under clods. Those 
that remained alive were mostly stupid and helpless. The beetles 
were Epicauta cinerea and Macrobasis unicolor, which are of only 
medium size. 

On July 25, 1914, a test was started at the Garden City branch of 
the Kansas Experiment Station on two tenth-acre plats that had 
been attacked by blister beetles to determine the comparative value of 
spraying and dusting. Paris green was used as a spray, 1 pound to 
25 gallons of water; as a dust. 1 pound to 5 pounds of powdered lime; 
and lead arsenate was used as a dust without dilution. Part of each 
plat was treated with each formula. There was no perceptible dif- 
ference in results. Of the small beetles (Epicauta maculata) a large 
percentage were killed, but of the large ones (Macrobasis se</)nentata 
Say, and Macrobasis vrrvmaculata) more escaped than were killed. 

DRIVING. 

When disturbed while feeding blister beetles drop or climb down 
rapidly to the ground and run away, sometimes traveling several 
yards before stopping to feed. Fields that are attacked by them may 
often be saved by taking advantage of this habit and driving them off. 
Several persons form a line and advance through the field, knocking 
the beetles from the plants with brooms, sticks, or pieces of brush. 
The advance should be slow, allowing time for killing any beetles that 
fall behind. At Garden City five persons in half a day drove the 
beetles out of 25 acres of beets. The method is to be recommended 
where most of the beetles are of the large varieties, where the plants 
are small and unable to survive defoliation if it occurs, or where for 
any reason immediate results must be secured. It is not practicable 
where abundant foliage affords concealment for the beetles. 

SUMMARY OF CONTROL MEASURES. 

Attacks by the smaller beetles are easily controlled by spraying 
with 1 pound of Paris green with lime in from 25 to 40 gallons of 
water. Many of the larger species are killed by the stronger solu- 
tion. Dusting with 1 pound of Paris green to 5 pounds of powdered 
lime or with pure lead arsenate is effective against the small beetles, 
but can not be recommended against the larger ones. Driving the 
beetles out of the field is recommended wherever the work of the 
beetles must be checked at once. 



26 BULLETIN 961, U. S. DEPARTMENT OF AGRICULTURE. 

The application of control measures for blister beetles must take 
into account the relation of these insects to grasshoppers. As long 
as the latter are present their eggs provide food for the young of the 
beetles. The destruction of the grasshopper eggs leaves the blister- 
beetle larvae without food, thus being doubly beneficial. Incorporat- 
ing into the farm practice of a community the simple measures that 
are known to hold grasshoppers in check will eliminate the danger 
from blister beetles. 



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